One type of prior art ink-jet printer has a printhead mounted to a carriage which is moved back and forth over print media, such as paper. As the printhead passes over appropriate locations on the print media, a control system activates the printhead to eject ink drops onto the print media and form desired images and characters. To work properly, such printers should have a reliable supply of ink for the printhead.
One category of ink-jet printer uses an ink supply that is mounted to and moves with the carriage. In some types, the ink supply is replaceable separately from the printhead. In others, the printhead and ink supply together form an integral unit that is replaced as a unit once the ink in the ink supply is depleted.
Another category of printer, referred to as an "off-axis" printing system, uses ink supplies which are not located on the carriage. One type replenishes the printhead intermittently. The printhead will travel to a stationary reservoir periodically for replenishment. U.S. patent application Ser. No. 09/034,719 now U.S. Pat. No. 6,170,937 describes another printing system wherein the printhead is fluidically coupled to a replaceable ink supply or container via a conduit such as a flexible tube. This allows the printhead to be continuously replenished during a printing operation.
In the parent application to this application, a replaceable off-axis ink container is described which has a memory device mounted to the housing. When inserted into the printer station, an electrical connection between the printer and the memory device is established. This electrical connection allows for the exchange of information between the printer and the memory. The memory device stores information which is utilized by the printer to ensure high print quality. This information is provided to the printer automatically when the cartridge is mounted to the printer. The exchange of information assures compatibility of the cartridge with the printer.
The stored information further prevents the use of the container after it is depleted of ink. Operating a printer when the reservoir has been depleted of ink may damage or destroy the printhead. The memory devices concerned with this application are updated with data from the printhead concerning the amount of ink left in the reservoir as it is being used. When a new cartridge is installed, the printer will read information from the memory device that is indicative of the reservoir volume. During usage, the printing system estimates ink usage and updates the memory device to indicate remaining ink in the cartridge. Once the ink in the ink container is substantially depleted, the memory device is updated to reflect an out-of-ink condition. The depleted of ink cartridges and memory devices are then discarded.